The present invention relates, in general, to dispensing of fluids, and more particularly, to a novel dispenser that accurately controls the amount of material dispensed.
In the past, the semiconductor industry had used dispensers to administer small amounts of viscous fluids onto semiconductor packages and other workpieces. These previous dispensers typically had a plunger which was used to push a material to be dispensed from the dispenser's storage cavity. As the plunger moved through the cavity, it pushed the material through the cavity and out a small opening or orifice in a nozzle.
One disadvantage of previous dispensers was controlling the distance that the plunger was withdrawn from the cavity in order to load the material into the cavity. Typically, the plunger was raised until encountering an abutment or stop that was machined into the dispenser's body. These abutments were not adjustable, consequently, it was difficult to accurately control the amount of material that was loaded into the cavity.
Another disadvantage of previous dispensers was the difficulty in creating a multiple nozzle dispensing system that could accurately control the amount of material that was dispensed from each nozzle. Previous dispensers typically had one adjustment which controlled the distance that the plunger was inserted into the cavity. When utilized in a multiple nozzle dispenser system, slight variations among the individual dispensers resulted in a non-uniform emission of material from the multiple nozzle dispenser system. The single adjustment could not provide sufficient control to compensate for the slight variations.
An additional disadvantage of previous dispensers was the method of feeding material into the dispenser. Previous dispensers typically had an input opening or port through which the material was pressure fed into the dispenser. The arrangement of these input ports required multiple nozzle dispenser systems to have a separate material supply connection to each nozzle.
A further disadvantage of previous dispensers was the dimensional stability of the nozzle's output orifice. Typically, these previous dispenser's nozzle was formed from plastic or other similar materials. After repeated usage, the size of the nozzle's orifice could increase thereby altering the rate at which the material was dispensed.
In addition, it was difficult to control the rate at which material was emitted from previous dispensers. Generally, the plunger was rapidly inserted into the dispenser's cavity thereby rapidly emitting the material.
Previous multiple nozzle dispenser systems generally did not permit only selected nozzles to dispense the material, but required every nozzle to dispense simultaneously.
Accordingly, it is desirable to have a dispenser that has a separate adjuster which can vary the distance that the plunger is withdrawn from the cavity, that has a separate adjuster which can vary the distance that the plunger is inserted into the cavity in order to control the amount of material dispensed, that has a nozzle which is made from a dimensionally stable material, that can be utilized in a multiple nozzle dispenser system without having a separate material input connection for each nozzle, and that can control the rate at which the material is dispensed through the nozzle.